<Snipped quote by Shorticus>
So how would the Namilee react to large bipedal reptiles with a clear carnivorous nature circling them in a non-hostile manner and sniffing?
Assuming they meet on land and not in space? Probably by vanishing via their camouflaging technology and trying to evade them before reevaluating their approach with these creatures.
If the Namilee were able to get the "jump," so to speak, they'd probably appear out of nowhere and make their presence known before trying to demonstrate through gesture they have no harmful intentions. They'd probably try to react in a reciprocal manner to the aliens, assuming the aliens weren't displaying clearly hostile behavior. Again: hostile behavior would probably prompt their retreat.